JP2004249243A - System for supplying material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system (device) for supplying materials which simply and inexpensively realizes the elongation of the life of an on-off valve which opens or closes according to the supply pressure to a discharge device. <P>SOLUTION: The system for supplying materials is arranged with a variable flow regulating valve 3 (a pressure reducing valve), an air-operated valve (an on-off valve) 4, and an accumulator 5 in this order from the side of a plunger pump 1 in a supply line S between the plunger pump 1 and a dispenser 2. The pressure in the vicinity of the suction port 2a of the dispenser 2 is detected by a pressure sensor 9, and on the basis of this pressure, opening or closing of the air-operated valve 4 is controlled through a solenoid valve 8. The accumulator 5 relieves the variation of pressure depending on variation in the volume of a second chamber housing materials to be supplied caused by a balance between the pressure of a secondary supply line S2 on the downstream of the variable flow regulation valve 3 (a pressure reducing valve) and the spring force of a spring 15. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a material supply system. For example, this system applies a fixed amount of a liquid material such as a sealant or fills a fixed amount of a liquid material such as an adhesive or grease to an automobile component or the like (hereinafter referred to as a work) in an automobile assembly plant. Used for systems (devices).
[0002]
[Prior art]
In an automobile assembly plant, a liquid material such as a sealant or an adhesive is sucked from a storage tank containing the same using a high-pressure pump called a plunger pump, and supplied to a supply line. It is widely used to supply a plurality of discharge devices (dispensers) through a branched branch line and apply or fill a workpiece by the discharge devices. In such a system, a high-pressure pump such as a plunger pump is used as a supply device because the material to be supplied needs to be supplied to a single or a plurality of locations (for example, a plurality of distant locations).
[0003]
For example, in the case of a system that supplies a sealant to a dispenser that applies a sealant (liquid material) to a work, the system is conventionally configured as illustrated in FIG. 3, for example. That is, the material to be supplied is sucked from the storage tank 108 by the plunger pump 101 and supplied to the supply line 102 in a high pressure state, and the primary side supply line 102 ′ on the supply side of the plunger pump 101 is 15 MPa (150 kg / cm ² ). It is kept at high pressure before and after. Then, the liquid is supplied to the dispenser 103 through the supply line 102, and the dispenser 103 directly discharges the liquid to the work to perform constant application or constant filling. Although not specifically shown, the supply line 102 from the plunger pump 101 is configured to branch and supply to a single or a plurality of locations (for example, distant locations).
[0004]
The supply line 102 is provided with a variable flow regulating valve 104 as a pressure reducing valve and an air operated valve 105 as an on-off valve in order from the pump 101 side to the dispenser 103 side, and the supply line 102 is located upstream of the pressure reducing valve 104. It has a high pressure primary supply line 102 ′ and a low pressure secondary supply line 102 ″ downstream of the pressure reducing valve 104. Here, the reason why the pressure of the secondary supply line 102 ″ (appropriate supply pressure to the dispenser 103) is small is that the dispenser 103 is mounted on a robot or the like for a work, so that it is small and lightweight. A device for dispensing a fixed amount is suitable (for example, a small-capacity uniaxial eccentric screw pump is used), and the discharge pressure of the coating liquid or the filling liquid by this device must be very small compared to the high-pressure pump on the supply side. Because it does not become. That is, the supply pressure to the dispenser 103 has an upper limit.
[0005]
A pressure sensor 106 for detecting the pressure in the vicinity of the suction port 103a of the dispenser 103 is provided. A pressure signal detected by the pressure sensor 106 is input to a solenoid valve 107, and the solenoid valve 107 controls opening and closing of the air operated valve 105 according to the pressure near the suction port 103a. The air operated valve 105 is closed when the pressure near the suction port 103a of the dispenser 103 (detected value of the pressure sensor 106) exceeds a set upper limit (for example, 0.7 MPa), and is set to a set lower limit (for example, 0.3 MPa). If it falls below, it will open.
[0006]
By the way, the dispenser (discharge device) repeats the discharge operation and the discharge stop operation, and in order to prevent a shortage of the material when the discharge operation is changed from the discharge stop operation to the discharge operation, the dispenser (discharge device) is disposed downstream of the pressure reducing valve 104. The pressure in the secondary supply line 102 '' (the supply line to the dispenser) must be maintained at some high pressure.
[0007]
Therefore, when the dispenser 103 stops the discharge operation, the pressure in the secondary supply line 102 ″ immediately rises and exceeds the set upper limit, and the air operated valve 105 (open / close valve) closes. Thereafter, when the discharge operation is started, the pressure immediately decreases to fall below the set lower limit value, and the air operated valve 105 is opened. As a result, each time the discharge operation / discharge stop operation of the dispenser 103 is repeated, the pressure exceeds the set upper limit value or falls below the set lower limit value, so that the opening / closing operation of the air operated valve 105 is frequently performed. When the opening and closing operation of the air operated valve 105 is performed frequently and the opening and closing frequency increases, the life of the air operated valve 105 may be shortened.
[0008]
In addition, the applicant interposes, in this order, a buffer pump composed of a pressure reducing valve, an on-off valve, and a single-shaft eccentric screw pump in a supply line between the supply device and the dispenser, and operates the buffer pump and operates the on-off valve. A device that controls the opening / closing operation based on the pressure in a supply line between the buffer pump and the dispenser has been proposed (for example, see Patent Document 1).
[0009]
[Patent Document 1]
JP-A-2002-316081 (paragraph numbers 0017 to 0020, FIG. 1)
[0010]
[Problems to be solved by the invention]
In the technique of Patent Document 1, by using a buffer pump, the pressure acting on the dispenser is reduced by reducing the pressure by a pressure reducing valve more than in the related art (see FIG. 3), or the dispenser is stopped or reversed. Although it is possible to prevent liquid dripping at the time, in the technique of Patent Document 1 as well, the opening and closing frequency of the on-off valve is high like the conventional one (FIG. 3), and the life of the on-off valve may be shortened. There is.
[0011]
The present invention has been made in view of the above points, and an object of the present invention is to provide a material supply system (apparatus) in which the life of the on-off valve described above is realized simply and inexpensively.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a material supply system according to the present invention includes a supply device that suctions a material to be supplied stored in a storage unit such as a storage tank and supplies the material in a high pressure state, and a discharge device that supplies a fixed amount to a workpiece. A supply line connecting a supply port of the supply device and a suction port of the discharge device and having a pressure-reducing valve and an on-off valve capable of setting a pressure reduction ratio, and a pressure near the suction port of the discharge device. A pressure sensor to be detected, based on a pressure signal from the pressure sensor, closes the on-off valve when the pressure near the suction port of the discharge device exceeds a set upper limit, and closes the on-off valve when the pressure falls below a set lower limit. In the material supply system comprising a control unit for opening the pressure reducing valve, a pressure reducing ratio of the pressure reducing valve to a supply line between the on-off valve and the suction port of the discharge device is lower than a pressure at which the entire amount flows during the operation of the discharge device. Characterized in that a suppressing accumulator to or below the set lower limit value or exceeds the set upper limit pressure in a short time in the vicinity of inlet of the discharge device in a state of being set to the pressure. That is, the material supply system according to the present invention combines a pressure-reducing valve capable of setting a pressure-reducing ratio and an accumulator, and drastically reduces the opening and closing operation of the on-off valve, which shortens its life when the on-off frequency of the on-off valve is high. is there.
[0013]
According to the material supply system of the present invention, the supply pressure to the discharge device during the discharge operation of the discharge device in a state where the pressure reduction ratio of the pressure reducing valve is set to a pressure lower than the pressure at which the entire amount flows during the operation of the discharge device If the (supply pressure of the secondary side supply line) falls below the set lower limit value (pressure at which the on-off valve is opened) and the supply of the material is insufficient, the internal volume (second chamber) of the accumulator decreases. Accordingly, the supply pressure to the discharge device (pressure of the secondary side supply line) does not fall below the set lower limit, and the accumulator compensates for the shortage of the material supply to the discharge device, and the shortage of the material does not occur. Become. On the other hand, when the discharge of the discharge device is stopped, even if the supply pressure to the discharge device (the pressure of the secondary supply line) exceeds the set upper limit value (the pressure at which the on-off valve is closed), the increase in the pressure is caused by the internal volume of the accumulator ( As the second chamber increases, it becomes absorbed. Thus, the supply pressure (pressure of the secondary supply line) to the discharge device exceeds the set upper limit value or falls below the set lower limit value by the combination of the pressure reducing valve and the accumulator in which the pressure reducing ratio is appropriately set. Since this is almost eliminated, the frequency of opening and closing the on-off valve is greatly reduced as compared with the conventional case, and the life of the on-off valve can be extended.
[0014]
More specifically, the average flow rate within a certain period of time is adjusted by the pressure reducing valve (by appropriately setting the pressure reducing ratio of the pressure reducing valve) in accordance with the repetition cycle of the discharge device and the discharge operation of the discharge device. Theoretically, the on-off valve will always be kept open. Therefore, if the flow rate is close to the average flow rate and slightly increased to the safe side, the frequency of opening and closing of the on-off valve is drastically reduced, and the occurrence of material supply shortage is avoided.
[0015]
Although the supply pressure to the discharge device is changed by the accumulator, the discharge device is characterized by having a quantitative property to supply a constant amount to the work, and therefore, there is a possibility that the discharge operation of the discharge device may be affected. Absent.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a schematic configuration diagram showing an overall configuration of a material supply system according to an embodiment of the present invention, and FIG. 2 is a sectional view showing an accumulator used in the system.
[0018]
This material supply system is used, for example, for applying a sealant (coating liquid) in an automobile production plant. As shown in FIG. 1, a plunger, which is a high-pressure pump, is transferred from a storage tank 6 for the sealant (material to be supplied). The sealant is sucked by the pump 1 (supply device), supplied to the supply line S in a high pressure state (around 15 MPa), and supplied to the dispenser 2 for applying a fixed amount of the sealant to a work (automobile component). Although not specifically shown, the supply line S from the plunger pump 1 is branched into a plurality of parts, and the supply line S is supplied to a single or a plurality of locations (for example, a plurality of remote dispensers). The same is true.
[0019]
In the supply line S, from the plunger pump 1 side to the dispenser 2 side, a variable flow rate regulating valve 3 as a pressure reducing valve (a pressure reducing ratio can be set), an air operated valve 4 as an on-off valve, and a spring type accumulator 5 Are provided in order. The supply line S connects between the supply port 1a of the plunger pump 1 and the suction port 2a of the dispenser 2, and has a high-pressure primary-side supply line S1 upstream of the variable flow control valve 3 (pressure reducing valve). And a secondary pressure supply line S2 in a low pressure state on the downstream side of the variable flow control valve 3 (pressure reducing valve).
[0020]
In the vicinity of the suction port 2a of the dispenser 2, a pressure sensor 9 for detecting the pressure near the suction port 2a is provided. A pressure signal detected by the pressure sensor 9 is input to a solenoid valve 8 (control means), and the solenoid valve 8 controls the opening and closing of the air operated valve 4 according to the pressure near the suction port 2a. In other words, the opening and closing of the air operated valve 4 is controlled by the solenoid valve 8 so that the pressure near the suction port 2a is maintained within a range of a preset value (pressure value). That is, when the pressure detected by the pressure sensor 9 exceeds a set upper limit (for example, 0.7 MPa) within the range of the pressure value, the air operated valve 4 is closed, and the set lower limit (for example, 0. When the pressure falls below 3 MPa), the air operated valve 4 is opened.
[0021]
The accumulator 5 is of a type in which the pressure is increased by filling (into the second chamber), is of a spring type so as not to require a control pipe such as an air pipe, and is configured as shown in FIG. That is, the casing 11 having a substantially cylindrical shape is constituted by the lower casing 12 and the upper casing 13 screwed to an upper portion of the lower casing 12. The lower casing 12 has a female screw portion 12a at an upper portion, and a lower portion of the upper casing 13 is a male screw portion 13a screwed to the female screw portion 12a.
[0022]
A piston 14 is slidably provided inside the casing 11, and the piston 14 allows the upper chamber 11A and the lower second chamber 11 (FIG. 2 shows a state where the volume of the second chamber is zero). The inside is partitioned. The first chamber 11A functions as a spring chamber in which the spring 15 is housed in a compressed state, and is formed to have substantially the same inner diameter as the spring diameter of the spring 15, and has a communication hole 13b at the upper end for communicating with the outside air. The internal pressure is equal to the atmospheric pressure. The spring 15 urges the piston 14 in a direction to reduce the volume of the second chamber.
[0023]
The lower casing 12 has a passage portion 12b that shares a part of the secondary supply line S2 at a lower portion, and the passage portion 12b is configured to be able to communicate with the second chamber via the communication portion 12c. . A seal member 16 for sealing between the piston 14 and the casing 11 is fitted to an outer peripheral portion of the piston 14, and a concave portion 14a in which a lower end portion of a spring 15 is located is formed at an upper portion.
[0024]
The dispenser 2 uses a small, vertically oriented uniaxial eccentric screw pump. As is well known, this screw pump has a female screw type stator formed of an elastic body having an elongated hole having a cross section that is continuous in a screw shape in the longitudinal direction, and a cross section that is slidably and rotatably inserted into the screw hole of the stator. A male external screw rotor that is circular and has a screw pitch of １ ／ the diameter of the screw hole, a connecting rod that is flexible and connected eccentrically from the center of one end face of the rotor, and a drive shaft is connected to the connecting rod. The motor is connected to an encoder.
[0025]
Subsequently, a usage mode of the material supply system of the present example will be described.
[0026]
(1) In FIG. 1, the sealing agent is sucked from the storage tank 6 by the plunger pump 1 and the high-pressure (in this example, 15 MPa) sealing agent is supplied to the supply line S, so that the primary-side supply line S1 Is maintained in a high pressure state (15 MPa in this example).
[0027]
The supply line S is connected to the dispenser 2, and the flow rate of the sealant is limited in the secondary supply line S 2 downstream of the supply line S by a variable flow control valve 3 (pressure reducing valve) provided in the middle thereof. (In this example, 4 MPa).
[0028]
(2) When the supply of the sealant to the dispenser 2 tends to be insufficient, the pressure in the secondary-side supply line S2 downstream of the variable flow control valve 3 is adjusted so that the supply of the sealant does not become insufficient. It is preferable that the adjustment be performed by the variable flow control valve 3.
[0029]
(3) A fixed amount of the sealant is discharged from the dispenser 2 to the work, and a predetermined width of application is performed along a planned application line on the work.
[0030]
(4) When a series of coating operations on the workpiece by the dispenser 2 is completed in this way, the operation of the dispenser 2 is stopped. In this case, conventionally, since the pressure near the suction port 2a of the dispenser 2 (the pressure detected by the pressure sensor 9) exceeds the set upper limit, the air operated valve 4 is closed. However, in the present embodiment, when the pressure in the secondary supply line S2 tends to increase, the sealant in the secondary supply line S2 is accumulated in the accumulator 5 (second chamber) and exceeds the set upper limit. Is avoided. In addition, when the operation of the dispenser 2 is started, the pressure (pressure detected by the pressure sensor 9) in the vicinity of the suction port 2a of the dispenser 2 is lower than the set lower limit value, so that the air operated valve 4 is opened. Was. However, in the present embodiment, when the pressure in the secondary supply line S2 is going to decrease, the sealant is supplied from the accumulator 5 (second chamber) into the secondary supply line S2, and the sealing agent falls below the set lower limit. Is avoided.
[0031]
That is, by providing the accumulator 5, if the pressure reduction ratio of the variable flow control valve 3 (pressure reducing valve) is appropriately set, the pressure in the vicinity of the suction port 2a of the dispenser 2 (the pressure of the secondary side supply line S2) Can be suppressed from exceeding the set upper limit or falling below the set lower limit. Thus, the pressure near the suction port 2a of the dispenser 2 can be maintained between the set upper limit and the set lower limit, so that the frequency of opening and closing the air operated valve 4 is drastically reduced.
[0032]
In the case where the supply device such as the plunger pump 1 and the discharge device such as the dispenser 2 correspond one-to-one, the variable flow rate adjusting valve 3 can be omitted by changing the setting of the discharge pressure of the plunger pump 1. There will be many.
[0033]
Here, the supply pressure of the material is changed by providing the accumulator 5, but since the dispenser 2 (uniaxial eccentric screw pump) also has a quantitative property in this case, the constant discharge of the sealant is not impaired.
[0034]
(5) Further, the dispenser 2 repeats the discharge operation and the discharge stop operation at a constant cycle, and requires a necessary amount of sealant when performing the discharge operation after the discharge stop operation. Since the shortage of the agent is supplemented by the sealing agent accumulated in the second chamber of the accumulator 5, it is not necessary to maintain the pressure of the secondary side supply line S2 as high as in the past. Therefore, the pressure can be reduced by the variable flow control valve 3 more than before (see FIG. 3), and the pressure in the secondary supply line S2 can be made lower than in the conventional case. It is no longer necessary to increase the pressure resistance performance as compared with the related art, and from this point, the life of the air operated valve 4 can be extended.
[0035]
The material supply system according to the present invention can be implemented as follows in addition to the above-described embodiment.
[0036]
(I) The present invention can be applied not only to a system for dispensing a fixed amount by a dispenser but also to a filling system for filling a fixed amount.
[0037]
(Ii) In addition to the above-described spring type, if the accumulator is of a type in which the pressure is increased by filling (into the second chamber), other types such as an air pressure control type may be used in addition to the spring. It is also possible to adopt.
[0038]
(Iii) The variable flow control valve 3 (pressure reducing valve) and the air operated valve 4 (opening / closing valve) may be of an electric control type in addition to the air control type.
[0039]
【The invention's effect】
As is apparent from the above description, the material supply system of the present invention has a pressure difference between the discharge operation and the discharge stop operation of the discharge device having a quantitative property in a state where the pressure reducing ratio of the pressure reducing valve is appropriately set. Is adjusted by changing the internal volume (second chamber) of the accumulator, so that the accumulator does not exceed the set upper limit for closing the on-off valve or fall below the set lower limit for opening the on-off valve. And the frequency of opening and closing the on-off valve can be drastically reduced. Since the frequency of opening and closing the on-off valve is drastically reduced, the life of the on-off valve can be extended.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an overall configuration of a material supply system according to an embodiment of the present invention.
FIG. 2 is a sectional view showing an accumulator used in the system.
FIG. 3 is a diagram showing an overall configuration of a conventional material supply system.
[Explanation of symbols]
S supply line 1 plunger pump (supply device)
1a supply port 2 dispenser (discharge device)
2a Suction port 3 Variable flow control valve (pressure reducing valve)
4 Air operated valve (open / close valve)
5 Accumulator 6 Storage tank 8 Solenoid valve (control means)
9 Pressure sensor 11 Casing 11A First chamber 12 Lower casing 12b Passage 12c Communication section 13 Upper casing 14 Piston 15 Spring

Claims (1)

A supply device that sucks and supplies the material to be supplied stored in a storage unit such as a storage tank in a high-pressure state, a discharge device that supplies a constant amount to the workpiece, and a space between a supply port of the supply device and a suction port of the discharge device. And a supply line provided with a pressure-reducing valve and an on-off valve capable of setting a pressure-reducing ratio, a pressure sensor for detecting a pressure near a suction port of the discharge device, and the discharge based on a pressure signal from the pressure sensor. A control means for closing the on-off valve when the pressure near the suction port of the device exceeds a set upper limit and opening the on-off valve when the pressure falls below a set lower limit.
In the supply line between the on-off valve and the suction port of the discharge device, the suction port of the discharge device in a state where the pressure reduction ratio of the pressure reducing valve is set to a pressure lower than the pressure at which the entire amount flows during the operation of the discharge device A material supply system provided with an accumulator that suppresses a nearby pressure from exceeding a set upper limit or falling below a set lower limit in a short time.

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